Environews

Nanotechnology in a Nutshell

Nanotechnology--the engineering, control, and exploitation of the unique chemical, physical, and electrical properties that emerge from man-made materials small enough to be measured in nanometers--is predicted to pour a whopping $1 trillion into the U.S. economy alone by 2015. But with the almost-magical properties of these minuscule building blocks and their promise of prosperity come a growing number of human and environmental health implications. The Focus (p. A740) looks at the pros and cons of nanotechnology.

Supplemental Reading

Since its 1994 passage, the Dietary Supplement Health and Education Act has been viewed by some as unleashing a flood of largely unregulated, pharmacologically active products onto an unwary public, with sometimes devastating results. The Spheres of Influence (p. A750) examines ways the Food and Drug Administration is working to improve oversight over botanical dietary supplements and what this may mean for industry.

New Life for Cotton Fibers

More than one-quarter of U.S. cotton fiber may be lost at various processing steps between harvesting and weaving. Now the Innovations (p. A754) describes a new use for this source of nearly pure cellulose. Using a relatively benign solvent, a team from Cornell Univesity is pressing waste cotton fibers into service as feedstock for electrospinning into nanofibers.

Research

Dioxin Revisited

Based on limited evidence in humans, sufficient evidence in experimental animals, and extensive information indicating a mechanism involving the aryl hydrocarbon receptor, the International Agency for Research on Cancer (IARC) classified 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as a group 1 carcinogen in 1997. This classification has been somewhat controversial. Steenland et al. (p. 1265) reviewed the epidemiologic and mechanistic evidence that has emerged since 1997 and conclude that the new evidence generally supports the 1997 IARC classification.

Science and Practice of Carcinogen Identification

Carcinogen identification is based on the scientific evaluation of the results of human epidemiologic studies, long-term bioassays in experimental animals, and other data relevant to an evaluation of carcinogenicity and its mechanisms. Cogliano et al. (p. 1269) discuss the science basis common to the evaluation of carcinogens across different programs, combined with detail on principles and procedures currently used by the IARC Monographs program.

Pesticide Use and Non-Hodgkin Lymphoma Risk

Kato et al. (p. 1275) conducted a population-based incidence case-control study among women in upstate New York to determine whether pesticide exposure is associated with increased risk of non-Hodgkin lymphoma (NHL). The risk of NHL was doubled among women who worked at least 10 years at a farm where pesticides were used. When both farming and other types of jobs associated with pesticide exposure were combined, there was a progressive increase in risk of NHL with increasing duration of such work. Although the results suggest an association between pesticide exposure and NHL in women, limitations related to selection and recall bias should be taken into account when inferring causation. (Also see Science Selections, p. A758)

Relating PM_2.5 Exposure to Mortality

Numerous epidemiologic studies have modeled mortality and morbidity responses to PM_2.5 levels using Poisson generalized additive models (GAMs). These models are useful, but they cannot directly measure the strength of the effect of exposure to PM_2.5 on mortality. Holloman et al. (p. 1282) propose a three-stage Bayesian hierarchical model as an alternative to the classical Poisson GAM. Fitting the model to data from seven North Carolina counties indicates that an increase in PM_2.5 is linked to increased cardiovascular mortality in the same day and the next 2 days. The authors also compare this model with frequentist and Bayesian versions of the classical Poisson GAM.

Serum Dioxin and Age at Menarche

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is associated with delayed pubertal development in animal studies. A 1976 chemical explosion in Seveso, Italy, produced the highest levels of TCDD exposure in a human population. Warner et al. (p. 1289) examined the association of TCDD serum levels, based on measurements in serum collected soon after the explosion, with reported age at menarche among women who were premenarcheal at the time of the explosion. Individual serum TCDD measurements were not significantly related to age at menarche among women in the cohort.

Biomonitoring of Cobalt and Tungsten Exposure

Exhaled breath condensate (EBC), a fluid formed by cooling exhaled air, is proposed as a suitable matrix to assess target tissue dose and effects of inhaled cobalt and tungsten, using EBC malondialdehyde (MDA) as a biomarker of pulmonary oxidative stress. Goldoni et al. (p. 1293) studied Co, W, and MDA in EBC among exposed and unexposed workers using mass spectrometric reference techniques. MDA levels were increased in EBC depending on Co concentration and were enhanced by coexposure to W. Results suggest that EBC may be useful in biomonitoring and health surveillance.

Particulate Matter and Systemic Microvascular Function

Acute exposure to particulate matter (PM) increases the risk of cardiovascular dysfunction, but the mechanisms by which PM evokes systemic effects is unclear. Nurkiewicz et al. (p. 1299) investigated whether pulmonary exposure to a PM surrogate, residual oil fly ash (ROFA), affects endothelium-dependent dilation in the systemic microcirculation of rats. Pulmonary exposure to ROFA affected endothelial rather than smooth muscle function. The authors observed an increase in venular leukocyte adhesion and rolling in ROFA-exposed rats, suggesting local inflammation at the systemic microvascular level. Results indicate that pulmonary PM exposure impairs systemic endothelium-dependent arteriolar dilation.

Decreased Toxicity with Low Sulfur Fuel and a Catalyzed Trap

McDonald et al. (p. 1307) studied the use of low sulfur fuel and a catalyzed trap to reduce the health hazard from diesel engine exhaust (DEE), which is associated with resistance to infection, inflammation, and oxidative stress. Lung toxicity assessments in mice were performed to compare uncontrolled (baseline) DEE emissions generated using 2003 certification fuel with those after emissions reduction using low sulfur fuel and a catalyzed particle trap. Baseline DEE produced significant biological effects for all measured parameters. Emissions reduction either completely or nearly eliminated the effects.

Developmental Dental Defects in Seveso Subjects

Alaluusua et al. (p. 1313) recruited 48 subjects from the contaminated areas of Seveso, Italy, for examination of dental and oral aberrations 25 years after the dioxin accident. Frozen serum samples were available for the exposed subjects but not for the matched subjects from surrounding zones. Of the subjects who had developmental enamel defects, 93% had been < 5 years of age at the time of the accident. The prevalence of defects in this age group correlated with serum TCDD levels (p = 0.016). The results support a hypothesis that dioxins can interfere with human organogenesis.

Environmental Medicine

Neurologic Abnormality and 1-Bromopropane Exposure

1-Bromopropane (1-BP), an alternative to ozone-depleting solvents, is a reproductive toxicant and neurotoxicant in rats. Ichihara et al. (p. 1319) examined the neurologic effects of 1-BP in workers and the relationship with exposure level. Exposed workers showed changes in vibration sense, distal latency, Benton test scores, and depression and fatigue in the Profile of Mood States when compared to age- and education-matched controls. The results indicate that 1-BP exposure adversely affects peripheral nerves and/or the central nervous system.

Subcutaneous Injection of Mercury:
A Case Report

Metallic mercury plays a major role in ethnic folk medicine. Prasad (p. 1326) reports a case of mercury injection for "warding off evil." Neurologic and renal complications can result from high systemic levels of mercury, and subcutaneous injection results in sterile abscesses. Key aspects of treatment are surgical evacuation, close monitoring for neurologic and renal functions, and chelation when toxicity is indicated. As increased immigration changes demographic patterns, prevention of the sale and use of mercury combined with its proper disposal become more urgent.

Children's Health

Water Arsenic and Child Intellectual Function

Exposure to arsenic has neurologic consequences in adults although there have been no well-controlled studies in children. Wasserman et al. (p. 1329) report results of a cross-sectional investigation of intellectual function in 10-year-old children of parents participating in a prospective cohort study of arsenic exposure in Araihazar, Bangladesh. Water arsenic was associated with reduced intellectual function, in a dose-response fashion, such that children drinking water containing > 50 µg/L As achieved significantly lower Performance and Full Scale scores than children drinking water containing < 5.5 µg/L As. (Also see Science Selections, p. A758)

Aflatoxin Exposure and Impaired Growth

Aflatoxins are dietary contaminants that are hepatocarcinogenic and immunotoxic and cause growth retardation in animals. Because aflatoxin exposure of West African children is known to be high, Gong et al. (p. 1334) conducted a longitudinal study over an 8-month period in Benin to assess the effects of exposure on growth. Results indicate a strong negative correlation (p < 0.0001) between aflatoxin-albumin adducts and height increase after adjustment for age, sex, height at recruitment, socioeconomic status, village, and weaning status. The study emphasises the association between aflatoxin and impaired growth, although the mechanisms remain unclear. (Also see Science Selections, p. A759)

Adolescents Exposed to DEHP as Neonates

Di-2-ethylhexyl phthalate (DEHP), used to make polyvinyl chloride (PVC) plastic tubing soft and flexible, is widely used in disposable PVC medical devices. Treatments that involve high DEHP exposures are blood exchange transfusions, extracorporeal membrane oxygenation (ECMO), and cardiovascular surgery. Rais-Bahrami et al. (p. 1339) studied 13 male and 6 female subjects at 14-16 years of age who had undergone ECMO as neonates. These adolescents showed no significant adverse effects on their physical growth and pubertal maturity. Thyroid, liver, renal, and male and female gonadal functions tested were within normal ranges for age and sex distribution.

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Last Updated: August 16, 2004